This investigation seeks to answer to what extent 1) nicotine replacement therapy in pregnant women who quit smoking increases serum antioxidants and lowers levels of oxidative stress compared to their baseline levels while smoking, and 2) serum antioxidants and oxidative stress differ in pregnant smokers who a) are randomized to a behavioral smoking cessation program b) are randomized to a behavioral therapy plus nicotine replacement group and c) who relapse to cigarette smoking.